umount.2: Revise MNT_FORCE description

MNT_FORCE does not allow a busy filesystem to be unmounted.  Only
MNT_DETACH allows that.  MNT_FORCE only tries to abort pending
transactions, in the hope that might help umount not to block,

Also, other filesystems than NFS support MNT_FORCE.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
NeilBrown 2017-08-08 15:49:58 +10:00 committed by Michael Kerrisk
parent 3c0e88e400
commit 7045e43809
1 changed files with 11 additions and 3 deletions

View File

@ -61,9 +61,17 @@ unmounts a target, but allows additional
controlling the behavior of the operation: controlling the behavior of the operation:
.TP .TP
.BR MNT_FORCE " (since Linux 2.1.116)" .BR MNT_FORCE " (since Linux 2.1.116)"
Force unmount even if busy. Ask the filesystem to abort pending requests before attempting the
This can cause data loss. unmount. This may allow the unmount to complete without waiting
(Only for NFS mounts.) for an inaccessible server. If, after aborting requests, some
processes still have active references to the filesystem, the
unmount will still fail. In Linux 4.12, only the filesystems
9p (2.6.16),
ceph (2.6.34),
cifs (2.6.12),
fuse (2.6.16),
lustre (3.11),
and NFS (2.1.116) respond to MNT_FORCE.
.TP .TP
.BR MNT_DETACH " (since Linux 2.4.11)" .BR MNT_DETACH " (since Linux 2.4.11)"
Perform a lazy unmount: make the mount point unavailable for new Perform a lazy unmount: make the mount point unavailable for new